/*
 * findoidjoins.c
 *
 * Copyright (c) 2002-2017, PostgreSQL Global Development Group
 *
 * src/tools/findoidjoins/findoidjoins.c
 */
#include "postgres_fe.h"

#include "catalog/pg_class.h"

#include "libpq-fe.h"
#include "pqexpbuffer.h"


int
main(int argc, char **argv)
{
    PGconn       *conn;
    PQExpBufferData sql;
    PGresult   *res;
    PGresult   *pkrel_res;
    PGresult   *fkrel_res;
    char       *fk_relname;
    char       *fk_nspname;
    char       *fk_attname;
    char       *pk_relname;
    char       *pk_nspname;
    int            fk,
                pk;                /* loop counters */

    if (argc != 2)
    {
        fprintf(stderr, "Usage:  %s database\n", argv[0]);
        exit(EXIT_FAILURE);
    }

    initPQExpBuffer(&sql);

    appendPQExpBuffer(&sql, "dbname=%s", argv[1]);

    conn = PQconnectdb(sql.data);
    if (PQstatus(conn) == CONNECTION_BAD)
    {
        fprintf(stderr, "connection error:  %s\n", PQerrorMessage(conn));
        exit(EXIT_FAILURE);
    }

    /* Get a list of relations that have OIDs */

    printfPQExpBuffer(&sql, "%s",
                      "SET search_path = public;"
                      "SELECT c.relname, (SELECT nspname FROM "
                      "pg_catalog.pg_namespace n WHERE n.oid = c.relnamespace) AS nspname "
                      "FROM pg_catalog.pg_class c "
                      "WHERE c.relkind = " CppAsString2(RELKIND_RELATION)
                      " AND c.relhasoids "
                      "ORDER BY nspname, c.relname"
        );

    res = PQexec(conn, sql.data);
    if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
    {
        fprintf(stderr, "sql error:  %s\n", PQerrorMessage(conn));
        exit(EXIT_FAILURE);
    }
    pkrel_res = res;

    /* Get a list of columns of OID type (or any OID-alias type) */

    printfPQExpBuffer(&sql, "%s",
                      "SELECT c.relname, "
                      "(SELECT nspname FROM pg_catalog.pg_namespace n WHERE n.oid = c.relnamespace) AS nspname, "
                      "a.attname "
                      "FROM pg_catalog.pg_class c, pg_catalog.pg_attribute a "
                      "WHERE a.attnum > 0"
                      " AND c.relkind = " CppAsString2(RELKIND_RELATION)
                      " AND a.attrelid = c.oid"
                      " AND a.atttypid IN ('pg_catalog.oid'::regtype, "
                      " 'pg_catalog.regclass'::regtype, "
                      " 'pg_catalog.regoper'::regtype, "
                      " 'pg_catalog.regoperator'::regtype, "
                      " 'pg_catalog.regproc'::regtype, "
                      " 'pg_catalog.regprocedure'::regtype, "
                      " 'pg_catalog.regtype'::regtype, "
                      " 'pg_catalog.regconfig'::regtype, "
                      " 'pg_catalog.regdictionary'::regtype) "
                      "ORDER BY nspname, c.relname, a.attnum"
        );

    res = PQexec(conn, sql.data);
    if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
    {
        fprintf(stderr, "sql error:  %s\n", PQerrorMessage(conn));
        exit(EXIT_FAILURE);
    }
    fkrel_res = res;

    /*
     * For each column and each relation-having-OIDs, look to see if the
     * column contains any values matching entries in the relation.
     */

    for (fk = 0; fk < PQntuples(fkrel_res); fk++)
    {
        fk_relname = PQgetvalue(fkrel_res, fk, 0);
        fk_nspname = PQgetvalue(fkrel_res, fk, 1);
        fk_attname = PQgetvalue(fkrel_res, fk, 2);

        for (pk = 0; pk < PQntuples(pkrel_res); pk++)
        {
            pk_relname = PQgetvalue(pkrel_res, pk, 0);
            pk_nspname = PQgetvalue(pkrel_res, pk, 1);

            printfPQExpBuffer(&sql,
                              "SELECT    1 "
                              "FROM \"%s\".\"%s\" t1, "
                              "\"%s\".\"%s\" t2 "
                              "WHERE t1.\"%s\"::pg_catalog.oid = t2.oid "
                              "LIMIT 1",
                              fk_nspname, fk_relname,
                              pk_nspname, pk_relname,
                              fk_attname);

            res = PQexec(conn, sql.data);
            if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
            {
                fprintf(stderr, "sql error:  %s\n", PQerrorMessage(conn));
                exit(EXIT_FAILURE);
            }

            if (PQntuples(res) != 0)
                printf("Join %s.%s.%s => %s.%s.oid\n",
                       fk_nspname, fk_relname, fk_attname,
                       pk_nspname, pk_relname);

            PQclear(res);
        }
    }

    PQclear(fkrel_res);

    /* Now, do the same for referencing columns that are arrays */

    /* Get a list of columns of OID-array type (or any OID-alias type) */

    printfPQExpBuffer(&sql, "%s",
                      "SELECT c.relname, "
                      "(SELECT nspname FROM pg_catalog.pg_namespace n WHERE n.oid = c.relnamespace) AS nspname, "
                      "a.attname "
                      "FROM pg_catalog.pg_class c, pg_catalog.pg_attribute a "
                      "WHERE a.attnum > 0"
                      " AND c.relkind = " CppAsString2(RELKIND_RELATION)
                      " AND a.attrelid = c.oid"
                      " AND a.atttypid IN ('pg_catalog.oid[]'::regtype, "
                      " 'pg_catalog.regclass[]'::regtype, "
                      " 'pg_catalog.regoper[]'::regtype, "
                      " 'pg_catalog.regoperator[]'::regtype, "
                      " 'pg_catalog.regproc[]'::regtype, "
                      " 'pg_catalog.regprocedure[]'::regtype, "
                      " 'pg_catalog.regtype[]'::regtype, "
                      " 'pg_catalog.regconfig[]'::regtype, "
                      " 'pg_catalog.regdictionary[]'::regtype) "
                      "ORDER BY nspname, c.relname, a.attnum"
        );

    res = PQexec(conn, sql.data);
    if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
    {
        fprintf(stderr, "sql error:  %s\n", PQerrorMessage(conn));
        exit(EXIT_FAILURE);
    }
    fkrel_res = res;

    /*
     * For each column and each relation-having-OIDs, look to see if the
     * column contains any values matching entries in the relation.
     */

    for (fk = 0; fk < PQntuples(fkrel_res); fk++)
    {
        fk_relname = PQgetvalue(fkrel_res, fk, 0);
        fk_nspname = PQgetvalue(fkrel_res, fk, 1);
        fk_attname = PQgetvalue(fkrel_res, fk, 2);

        for (pk = 0; pk < PQntuples(pkrel_res); pk++)
        {
            pk_relname = PQgetvalue(pkrel_res, pk, 0);
            pk_nspname = PQgetvalue(pkrel_res, pk, 1);

            printfPQExpBuffer(&sql,
                              "SELECT    1 "
                              "FROM \"%s\".\"%s\" t1, "
                              "\"%s\".\"%s\" t2 "
                              "WHERE t2.oid = ANY(t1.\"%s\")"
                              "LIMIT 1",
                              fk_nspname, fk_relname,
                              pk_nspname, pk_relname,
                              fk_attname);

            res = PQexec(conn, sql.data);
            if (!res || PQresultStatus(res) != PGRES_TUPLES_OK)
            {
                fprintf(stderr, "sql error:  %s\n", PQerrorMessage(conn));
                exit(EXIT_FAILURE);
            }

            if (PQntuples(res) != 0)
                printf("Join %s.%s.%s []=> %s.%s.oid\n",
                       fk_nspname, fk_relname, fk_attname,
                       pk_nspname, pk_relname);

            PQclear(res);
        }
    }

    PQclear(fkrel_res);

    PQclear(pkrel_res);

    PQfinish(conn);

    termPQExpBuffer(&sql);

    exit(EXIT_SUCCESS);
}
